Coated abrasive articles are commonly used for abrading, grinding and polishing operations in both commercial and industrial applications. These operations are conducted on a wide variety of substrates, including wood, wood-like materials, plastics, fiberglass, soft metals, enamel surfaces, and painted surfaces. Some coated abrasives can be used in either wet or dry environments. In wet environments, common applications include filler sanding, putty sanding, primer sanding and paint finishing.
In general, these abrasive articles include a paper or polymeric backing on which abrasive particles are adhered. The abrasive particles may be adhered using one or more tough and resilient binders to secure the particles to the backing during an abrading operation. In a manufacturing process, these binders are often processed in a flowable state to coat the backing and the particles, and then subsequently hardened to lock in a desired structure and provide the finished abrasive product.
In a common construction, the backing has a major surface that is first coated with a “make” layer. Abrasive particles are then deposited onto the make layer such that the particles are at least partially embedded in the make layer. The make layer is then hardened (e.g., crosslinked) to secure the particles. Then, a second layer called a “size” layer is coated over the make layer and abrasive particles and also hardened. The size layer further stabilizes the particles and also enhances the strength and durability of the abrasive article. Optionally, additional layers may be added to modify the properties of the coated abrasive article.
A coated abrasive article can be evaluated based on certain performance properties. First, such an article should have a desirable balance between cut and finish—that is, an acceptable efficiency in removing material from the workpiece, along with an acceptable smoothness of the finished surface. Second, an abrasive article should also avoid excessive “loading”, or clogging, which occurs when debris or swarf become trapped between the abrasive particles and hinder the cutting ability of the coated abrasive. Third, the abrasive article should be both flexible and durable to provide for longevity in use.
Wet abrasive applications can provide unique challenges. Abrasive sheets may be soaked in water for extended periods of time, sometimes for more than 24 hours. A particular problem encountered with commercial coated abrasive articles in wet environments is the tendency for these coated articles to curl. Curling of the abrasive article can be a significant nuisance to the user. A similar effect can also occur when abrasive articles are stored in humid environments. To mitigate curling, abrasive sheets are sometimes pre-flexed in the manufacturing process, but this is generally ineffective in preventing curling during use.
The present disclosure provides coated abrasive articles in which the make layer, abrasive particle layer, and size layer are coated onto a backing in a discontinuous coating pattern. All three components are substantially in registration with each other according to discrete pattern features, thereby providing pervasive uncoated areas extending across the backing. The features optionally have an areal density ranging from about 30 features to about 300 features per square centimeter and an average feature diameter ranging from about 0.1 millimeters to about 1.5 millimeters. The provided abrasive particles optionally have an average abrasive particle size ranging from about 20 micrometers to about 250 micrometers and the average make layer thickness ranging from 33 percent to 100 percent of the average abrasive particle size. Advantageously, this configuration provides a coated abrasive that displays superior curl-resistance and improved overall cut and finish performance as compared with prior art abrasive articles.
In one aspect, an abrasive article is provided. The abrasive article comprises: a flexible backing having a major surface; a make resin contacting the major surface and extending across the major surface in a pre-determined pattern; abrasive particles contacting the make resin and generally in registration with the make resin as viewed in directions normal to the plane of the major surface; and a size resin contacting both the abrasive particles and the make resin, the size resin being generally in registration with both the abrasive particles and the make resin as viewed in directions normal to the plane of the major surface, wherein areas of the major surface contacting the make resin are generally coplanar with areas of the major surface not contacting the make resin, and wherein the pre-determined pattern comprises a multiplicity of features having an areal density ranging from about 30 features to about 300 features per square centimeter and an average feature diameter ranging from about 0.1 millimeters to about 1.5 millimeters.
In another aspect, an abrasive article is provided comprising: a flexible backing having a major surface; a make resin contacting the major surface and extending across the major surface in a pre-determined pattern, the make resin layer having an average make layer thickness; abrasive particles contacting the make resin and generally in registration with the make resin as viewed in directions normal to the plane of the major surface, the abrasive particles having an average abrasive particle size ranging from about 20 micrometers to about 250 micrometers and the average make layer thickness ranging from 33 percent to 100 percent of the average abrasive particle size; and a size resin contacting both the abrasive particles and the make resin, the size resin being generally in registration with both the abrasive particles and the make resin as viewed in directions normal to the plane of the major surface, wherein areas of the major surface contacting the make resin are generally coplanar with areas of the major surface not contacting the make resin.
In still another aspect, an abrasive article is provided, comprising: a flexible backing having a generally planar major surface; and a plurality of discrete islands on the major surface arranged according to a two-dimensional pattern, each island comprising: a make resin contacting the backing; abrasive particles contacting the make resin; and a size resin contacting the make resin, the abrasive particles, and the backing, wherein areas of the major surface surrounding the islands do not contact the make resin, abrasive particles, or size resin, and wherein the pre-determined pattern comprises a multiplicity of features having an areal density ranging from about 30 features to about 300 features per square centimeter and an average feature diameter ranging from about 0.1 millimeters to about 1.5 millimeters.
In yet another aspect, an abrasive article comprising: a flexible backing having a generally planar major surface; and a plurality of discrete islands on the major surface arranged according to a two-dimensional pattern, each island comprising: a make resin contacting the backing, the make resin layer having an average make layer thickness; abrasive particles contacting the make resin, the abrasive particles having an average abrasive particle size ranging from about 20 micrometers to about 250 micrometers and the average make layer thickness ranging from 33 percent to 100 percent of the average abrasive particle size; and a size resin contacting the make resin, the abrasive particles, and the backing, wherein areas of the major surface surrounding the islands do not contact the make resin, abrasive particles, or size resin.